1. Field of the Invention
The present invention relates to a prosthesis intended to be anchored in a long bone.
2. History of the Related Art
This type of prosthesis conventionally comprises a stem intended to be inserted in the medullary cavity of the bone, extended by a metaphyseal part connected to a flange allowing bearing on the metaphysis of the bone.
This type of prosthesis can be implanted in particular at the upper end of a humerus, a femur or a tibia, for example in the event of fracture or of disorders such as arthrosis or polyarthritis.
After this prosthesis has been inserted in the bone, the osteosynthesis induces an intimate bonding of the prosthesis and the bone. In effect, the metaphysis of the bone is reconstituted around the corresponding part of the prosthesis and forms protuberances cooperating with reinforcements of the prosthesis, and even an osseous bridge if this latter is provided with a through hole.
However, such intimate bonding and the presence of protuberances or of an osseous bridge may prove to be detrimental, in those cases where it is necessary to remove the prosthesis, particularly in the event of a subsequent operation. In that case, it is necessary to break the reconstituted metaphysis by means of appropriate tools, such as a chisel, bone cutter or drill.
However, this operation proves to be particularly delicate. In effect, the presence of the flange hinders access to the metaphysis of the bone, which lies in the vicinity of that face of the flange opposite the one accessible to the surgeon. He must therefore damage the bone at the lateral surfaces of the flange in order to have access to the metaphysis. Apart from the fact that this operation is delicate for the surgeon, it induces a degradation of the bone over an important surface thereof.
In order to overcome this problem, one known solution consists in providing a prosthesis of which the flange is removable with respect to the stem. Consequently, in the event of subsequent operation or the like, the surgeon removes the removable flange so as to have direct access to the reconstituted metaphysis. However, this solution firstly presents a drawback from the economical standpoint, connected with the mechanical complexity of the prosthesis and the resulting additional costs. Moreover, being given that this prosthesis is inserted in an organic medium, the mechanical elements ensuring the removable clipping of the flange on the stem may be blocked by tissues.
It is therefore an object of the invention to provide a prosthesis which overcomes the drawbacks of the prior art set forth hereinabove.